Method for making a chlorohydrin by chlorinating a polyhydroxylated aliphatic hydrocarbon

ABSTRACT

Process for preparing a chlorohydrin, comprising the following steps:
         (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof whose alkali metal and/or alkaline earth metal content is less than or equal to 5 g/kg, a chlorinating agent and an organic acid are reacted so as to give a mixture containing at least chlorohydrin and by-products   (b) at least part of the mixture obtained in step (a) is subjected to one or more treatments in steps subsequent to step (a)   (c) at least one of the steps subsequent to step (a) consists in oxidation at a temperature greater than or equal to 800° C.

The present patent application is a 371 of PCT/EP2006/062444 filed May19, 2006. The present patent application claims the benefit of patentapplication FR 05.05120 and of patent application EP 05104321.4, bothfiled on 20 May 2005, and of provisional U.S. patent applications60/734,659, 60/734,627, 60/734,657, 60/734,658, 60/734,635, 60/734,634,60/734,637 and 60/734,636, all filed on 8 Nov. 2005, the content of allof which is incorporated here by reference.

The present invention relates to a process for preparing a chlorohydrin,more specifically to a process for preparing a chlorohydrin bychlorinating a polyhydroxylated aliphatic hydrocarbon.

Chlorohydrins are reaction intermediates in the preparation of epoxides.Dichloropropanol, for example, is a reaction intermediate in thepreparation of epichlorohydrin and of epoxy resins (Kirk-OthmerEncyclopedia of Chemical Technology, Fourth Edition, 1992, Vol. 2, page156, John Wiley & Sons, Inc.).

According to known processes it is possible to obtain dichloropropanolin particular by hypochlorinating allyl chloride, by chlorinating allylalcohol and by hydrochlorinating glycerol. This latter process has theadvantage that the dichloropropanol can be obtained starting from fossilraw materials or from renewable raw materials, and it is known thatnatural petrochemical resources, from which the fossil materials areobtained, such as petroleum, natural gas or coal, for example, arelimited in their terrestrial availability.

Application WO 2005/054167 of SOLVAY SA describes a process forpreparing dichloropropanol by reacting glycerol with hydrogen chloridein the presence of a catalyst such as adipic acid as catalyst. In thisprocess the dichloropropanol is separated from the other products of thereaction and the latter are recycled to the glycerol chlorinationreactor. It is possible to take off a fraction of these other reactionproducts via a purge and to subject said fraction to various treatmentprior to possible discharge. Discharge does not constitute a solutionwhich is acceptable from an environmental standpoint. Moreover, theextra cost associated with the pre-discharge treatment may beprohibitive for the economics of the process.

The objective of the invention is to provide a process for preparing achlorohydrin that does not exhibit these drawbacks.

The invention accordingly provides a process for preparing achlorohydrin, comprising the following steps:

-   (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a    polyhydroxylated aliphatic hydrocarbon or a mixture thereof whose    alkali metal and/or alkaline earth metal content is less than or    equal to 5 g/kg, a chlorinating agent and an organic acid are    reacted so as to give a mixture containing at least chlorohydrin and    other compounds-   (b) at least part of the mixture obtained in step (a) is subjected    to one or more treatments in steps subsequent to step (a)-   (c) at least one of the steps subsequent to step (a) consists in    oxidation at a temperature greater than or equal to 800° C.

It has been found that, by using, in step (a) of the process, apolyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylatedaliphatic hydrocarbon or a mixture thereof which has an alkali metaland/or alkaline earth metal content of less than or equal to 5 g/kg itis possible to subject a part of the mixture obtained in step (a) tooxidation at a temperature greater than or equal to 800° C., and toobtain the following advantages:

-   1) recovery of the chlorinating agent;-   2) recovery of the useful energy content of the compounds of the    reaction mixture;-   3) reduction in the amount and toxicity of the compounds for    discharge.

Without wishing to be bound by any particular theoretical explanation,it is thought that the oxidation at a temperature greater than or equalto 800° C. can be conducted under satisfactory conditions because theformation of deposits in the oxidation plant and the risk of degradationto its refractory materials are reduced as a result of the low alkalimetal and/or alkaline earth metal content of the compounds burnt.

The term “polyhydroxylated aliphatic hydrocarbon” refers to ahydrocarbon which contains at least two hydroxyl groups attached to twodifferent saturated carbon atoms. The polyhydroxylated aliphatichydrocarbon may contain, but is not limited to, from 2 to 60 carbonatoms.

Each of the carbons of a polyhydroxylated aliphatic hydrocarbon bearingthe hydroxyl functional group (OH) cannot possess more than one OH groupand must have sp3 hybridization. The carbon atom carrying the OH groupmay be primary, secondary or tertiary. The polyhydroxylated aliphatichydrocarbon used in the present invention must contain at least twosp3-hybridized carbon atoms carrying an OH group. The polyhydroxylatedaliphatic hydrocarbon includes any hydrocarbon containing a vicinal diol(1,2-diol) or a vicinal triol (1,2,3-triol), including the higher,vicinal or contiguous orders of these repeating units. The definition ofthe polyhydroxylated aliphatic hydrocarbon also includes, for example,one or more 1,3-, 1,4-, 1,5- and 1,6-diol functional groups. Thepolyhydroxylated aliphatic hydrocarbon may also be a polymer such aspolyvinyl alcohol. Geminal diols, for example, are excluded from thisclass of polyhydroxylated aliphatic hydrocarbons.

The polyhydroxylated aliphatic hydrocarbons may contain aromaticmoieties or heteroatoms, including, for example, heteroatoms of halogen,sulphur, phosphorus, nitrogen, oxygen, silicon and boron type, andmixtures thereof.

Polyhydroxylated aliphatic hydrocarbons which can be used in the presentinvention comprise, for example, 1,2-ethanediol (ethylene glycol),1,2-propanediol (propylene glycol), 1,3-propanediol,1-chloro-2,3-propanediol (chloropropanediol), 2-chloro-1,3-propanediol(chloropropanediol), 1,4-butanediol, 1,5-pentanediol, cyclohexanediols,1,2-butanediol, 1,2-cyclohexanedimethanol, 1,2,3-propanetriol (alsoknown as “glycerol” or “glycerin”), and mixtures thereof. Withpreference the polyhydroxylated aliphatic hydrocarbon used in thepresent invention includes, for example, 1,2-ethanediol,1,2-propanediol, 1,3-propanediol, chloropropanediol and1,2,3-propanetriol, and mixtures of at least two thereof. Morepreferably the polyhydroxylated aliphatic hydrocarbon used in thepresent invention includes, for example, 1,2-ethanediol,1,2-propanediol, chloropropanediol and 1,2,3-propanetriol, and mixturesof at least two thereof. 1,2,3-Propanetriol or glycerol is the mostpreferred.

The esters of polyhydroxylated aliphatic hydrocarbon may be present inthe polyhydroxylated aliphatic hydrocarbon and/or may be produced in theprocess for preparing the chlorohydrin and/or may be prepared prior tothe process for preparing the chlorohydrin. Examples of esters of thepolyhydroxylated aliphatic hydrocarbon comprise ethylene glycolmonoacetate, propanediol monoacetates, glycerol monoacetates, glycerolmonostearates, glycerol diacetates and mixtures thereof.

The term “chlorohydrin” is used here in order to describe a compoundcontaining at least one hydroxyl group and at least one chlorine atomattached to different saturated carbon atoms. A chlorohydrin whichcontains at least two hydroxyl groups is also a polyhydroxylatedaliphatic hydrocarbon. Accordingly the starting material and the productof the reaction may each be chlorohydrins. In that case the “product”chlorohydrin is more chlorinated than the starting chlorohydrin, inother words has more chlorine atoms and fewer hydroxyl groups than thestarting chlorohydrin. Preferred chlorohydrins are chloroethanol,chloropropanol, chloropropanediol, dichloropropanol and mixtures of atleast two thereof. Dichloropropanol is particularly preferred.Chlorohydrins which are more particularly preferred are 2-chloroethanol,1-chloropropan-2-ol, 2-chloropropan-1-ol, 1-chloropropane-2,3-diol,2-chloropropane-1,3-diol, 1,3-dichloropropan-2-ol,2,3-dichloropropan-1-ol and mixtures of at least two thereof.

The polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon, or the mixture thereof in theprocess according to the invention may be obtained starting from fossilraw materials or starting from renewable raw materials, preferablystarting from renewable raw materials.

By fossil raw materials are meant materials obtained from the processingof petrochemical natural resources, such as petroleum, natural gas andcoal, for example. Among these materials preference is given to organiccompounds containing 2 and 3 carbon atoms. When the polyhydroxylatedaliphatic hydrocarbon is glycerol, allyl chloride, allyl alcohol and“synthetic” glycerol are particularly preferred. By “synthetic” glycerolis meant a glycerol generally obtained from petrochemical resources.When the polyhydroxylated aliphatic hydrocarbon is ethylene glycol,ethylene and “synthetic” ethylene glycol are particularly preferred. By“synthetic” ethylene glycol is meant an ethylene glycol generallyobtained from petrochemical resources. When the polyhydroxylatedaliphatic hydrocarbon is propylene glycol, propylene and “synthetic”propylene glycol are particularly preferred. By “synthetic” propyleneglycol is meant a propylene glycol generally obtained from petrochemicalresources.

By renewable raw materials are meant materials obtained from theprocessing of renewable natural resources. Among these materialspreference is given to “natural” ethylene glycol, “natural” propyleneglycol and “natural” glycerol. “Natural” ethylene glycol, propyleneglycol and glycerol are obtained for example by conversion of sugars bythermochemical processes, it being possible for these sugars to beobtained starting from biomass, as described in “Industrial Bioproducts:Today and Tomorrow”, Energetics, Incorporated for the U.S. Department ofEnergy, Office of Energy Efficiency and Renewable Energy, Office of theBiomass Program, July 2003, pages 49, 52 to 56. One of these processesis, for example, the catalytic hydrogenolysis of sorbitol obtained bythermochemical conversion of glucose. Another process is, for example,the catalytic hydrogenolysis of xylitol obtained by hydrogenation ofxylose. The xylose may for example be obtained by hydrolysis of thehemicellulose present in maize fibres. By “natural glycerol” or“glycerol obtained from renewable raw materials” is meant, inparticular, glycerol obtained during the production of biodiesel or elseglycerol obtained during conversions of animal or vegetable oils or fatsin general, such as saponification, transesterification or hydrolysisreactions.

Among the oils which can be used in the process of the invention,mention may be made of all common oils, such as palm oil, palm kerneloil, copra oil, babassu oil, former or new (low erucic acid) colza oil,sunflower oil, maize oil, castor oil and cotton oil, peanut oil, soyabean oil, linseed oil and crambe oil, and all oils obtained, forexample, from sunflower plants or colza plants obtained by geneticmodification or hybridization.

It is also possible to employ used frying oils, various animal oils,such as fish oils, tallow, lard and even squaring greases.

Among the oils used mention may also be made of oils which have beenpartly modified by means, for example, of polymerization oroligomerization, such as, for example, the “stand oils” of linseed oiland of sunflower oil, and blown vegetable oils.

A particularly suitable glycerol may be obtained during the conversionof animal fats. Another particularly suitable glycerol may be obtainedduring the production of biodiesel. A third, very suitable glycerol maybe obtained during the conversion of animal or vegetable oils or fats bytransesterification in the presence of a heterogeneous catalyst, asdescribed in documents FR 2752242, FR 2869612 and FR 2869613. Morespecifically, the heterogeneous catalyst is selected from mixed oxidesof aluminium and zinc, mixed oxides of zinc and titanium, mixed oxidesof zinc, titanium and aluminium, and mixed oxides of bismuth andaluminium, and the heterogeneous catalyst is employed in the form of afixed bed. This latter process can be a process for producing biodiesel.

The latter process has at least two advantages over the processes basedon saponification, transesterification or hydrolysis reactions which donot employ a heterogeneous catalyst. The first advantage is that thecontamination of the glycerol with alkali metal and/or alkaline earthmetal elements is reduced. These elements originate, for example, fromthe homogeneous basic reagents used in the transesterification orsaponification reactions (alkaline bases) or originate from operationsof neutralizing, using alkaline bases, the acidic homogeneous catalystsused during transesterification or acidic hydrolysis reactions. The useof heterogeneous catalysts as described above makes it possiblesubstantially to reduce the contamination of the glycerol with alkalimetal and alkaline earth metal elements, and also with other metallicelements. The second advantage is that the contamination of the glycerolwith non-glyceric organic matter is reduced. This non-glyceric matterincludes, for example, carboxylic acids, salts of carboxylic acids,fatty acid esters such as mono-, di- and triglycerides and the esters offatty acids with the alcohols used in the transesterification.

In the process for preparing a chlorohydrin according to the invention,the polyhydroxylated aliphatic hydrocarbon may be as described in thepatent application entitled “Process for preparing chlorohydrin byconverting polyhydroxylated aliphatic hydrocarbons”, filed in the nameof SOLVAY SA on the same day as the present application, and the contentof which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinwherein a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof whose totalmetal content, expressed in elemental form, is greater than or equal to0.1 μg/kg and less than or equal to 1000 mg/kg is reacted with achlorinating agent.

In the process according to the invention it is preferred to useglycerol obtained starting from renewable raw materials.

In the process for preparing a chlorohydrin according to the invention,the polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon or the mixture thereof may be acrude product or a purified product, such as are specifically disclosedin application WO 2005/054167 of SOLVAY SA, from page 2 line 8 to page 4line 2.

In the process for preparing a chlorohydrin according to the invention,the alkali metal and/or alkaline earth metal content of thepolyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylatedaliphatic hydrocarbon or the mixture thereof is less than or equal to 5g/kg, often less than or equal to 1 g/kg, more particularly less than orequal to 0.5 g/kg and in certain cases less than or equal to 0.01 g/kg.The alkali metal and/or alkaline earth metal content of the glycerol isgenerally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the inventionthe alkali metals are generally lithium, sodium, potassium and cesium,often sodium and potassium, and frequently sodium.

In the process for preparing a chlorohydrin according to the invention,the lithium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the invention,the sodium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the invention,the potassium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the invention,the rubidium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the invention,the cesium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the inventionthe alkaline earth metal elements are generally magnesium, calcium,strontium and barium, often magnesium and calcium and frequentlycalcium.

In the process for preparing a chlorohydrin according to the invention,the magnesium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the invention,the calcium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the invention,the strontium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the invention,the barium content of the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon or the mixture thereofis generally less than or equal to 1 g/kg, often less than or equal to0.1 g/kg and more particularly less than or equal to 2 mg/kg. Thiscontent is generally greater than or equal to 0.1 μg/kg.

In the process for preparing a chlorohydrin according to the inventionthe alkali and/or alkaline earth metals are generally present in theform of salts, frequently in the form of chlorides, sulphates andmixtures thereof. Sodium chloride is the most often encountered.

In the process for preparing a chlorohydrin according to the invention,the polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon or the mixture thereof maycontain elements other than alkali metals and alkaline earth metals.Among such elements consideration may be given to sulphur, iron, nickel,chromium, copper, lead, arsenic, cobalt, titanium, vanadium, tin,tellurium, cadmium, antimony, mercury, selenium, zinc, aluminium,phosphorus and nitrogen. These elements may be located in the secondportion obtained in step (b). Within the glycerol the sulphur content isgenerally less than or equal to 500 mg/kg and the nitrogen content isgenerally less than or equal to 500 mg/kg. The amount of metallicelements other than alkali metals and alkaline earth metals is generallyless than or equal to 1 mg/kg for each of these elements, preferablyless than or equal to 0.5 mg/kg.

In the process for preparing a chlorohydrin according to the invention,the chlorinating agent may be as described in application WO 2005/054167of SOLVAY SA, from page 4 line 25 to page 6 line 2.

In the process for preparing a chlorohydrin according to the invention,the chlorinating agent may be hydrogen chloride as described inapplication WO 2005/054167 of SOLVAY SA, from page 4 line 30 to page 6line 2.

Particular mention is made of a chlorinating agent which may be aqueoushydrochloric acid or hydrogen chloride which is preferably anhydrous.The hydrogen chloride may originate from a process for pyrolysingorganic chlorine compounds, such as, for example, from a vinyl chlorideproduction, from a process for producing 4,4-methylenediphenyldiisocyanate (MDI) or toluene diisocyanate (TDI), from metal picklingprocesses or from the reaction of an inorganic acid such as sulphuric orphosphoric acid with a metal chloride such as sodium chloride, potassiumchloride or calcium chloride.

In one advantageous embodiment of the process for preparing achlorohydrin according to the invention, the chlorinating agent isgaseous hydrogen chloride or an aqueous solution of hydrogen chloride,or a combination of the two.

In the process for preparing a chlorohydrin according to the invention,the hydrogen chloride may be an aqueous solution of hydrogen chloride ormay be preferably anhydrous hydrogen chloride, obtained from a plant forproducing allyl chloride and/or for producing chloromethanes and/or achlorinolysis plant and/or a plant for high-temperature oxidation ofchlorine compounds, as described in the application entitled “Processfor preparing a chlorohydrin by reacting a polyhydroxylated aliphatichydrocarbon with a chlorinating agent”, filed in the name of SOLVAY SAon the same day as the present application, and the content of which isincorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinfrom a polyhydroxylated aliphatic hydrocarbon, from an ester of apolyhydroxylated aliphatic hydrocarbon or from a mixture thereof, andfrom a chlorinating agent, the chlorinating agent comprising at leastone of the following compounds: nitrogen, oxygen, hydrogen, chlorine, anorganic hydrocarbon compound, an organic halogen compound, an organicoxygen compound and a metal.

Particular mention is made of an organic hydrocarbon compound which isselected from saturated or unsaturated aliphatic and aromatichydrocarbons and mixtures thereof.

Particular mention is made of an unsaturated aliphatic hydrocarbon whichis selected from acetylene, ethylene, propylene, butene, propadiene,methylacetylene and mixtures thereof, of a saturated aliphatichydrocarbon which is selected from methane, ethane, propane, butane andmixtures thereof and of an aromatic hydrocarbon which is benzene.

Particular mention is made of an organic halogen compound which is anorganic chlorine compound selected from chloromethanes, chloroethanes,chloropropanes, chlorobutanes, vinyl chloride, vinylidene chloride,monochloropropenes, perchloroethylene, trichloroethylene,chlorobutadienes, chlorobenzenes and mixtures thereof.

Particular mention is made of an organic halogen compound which is anorganic fluorine compound selected from fluoromethanes, fluoroethanes,vinyl fluoride, vinylidene fluoride and mixtures thereof.

Particular mention is made of an organic oxygen compound which isselected from alcohols, chloroalcohols, chloroethers and mixturesthereof.

Particular mention is made of a metal selected from alkali metals,alkaline earth metals, iron, nickel, copper, lead, arsenic, cobalt,titanium, cadmium, antimony, mercury, zinc, selenium, aluminium, bismuthand mixtures thereof.

Mention is made more particularly of a process wherein the chlorinatingagent is obtained at least partly from a process for preparing allylchloride and/or a process for preparing chloromethanes and/or a processof chlorinolysis and/or a process for oxidizing chlorine compounds at atemperature greater than or equal to 800° C.

In one particularly advantageous embodiment of the process for preparinga chlorohydrin according to the invention, the hydrogen chloride is anaqueous solution of hydrogen chloride and does not contain gaseoushydrogen chloride.

In the process for preparing a chlorohydrin according to the invention,the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon or the mixture thereof with thechlorinating agent may be carried out in a reactor as described inapplication WO 2005/054167 of SOLVAY SA on page 6 lines 3 to 23.

Mention is made particularly of a plant made of or covered withmaterials which are resistant, under the reaction conditions, to thechlorinating agents, particularly to hydrogen chloride. Mention is mademore particularly of a plant made of enamelled steel or of tantalum.

In the process for preparing a chlorohydrin according to the invention,the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester ofthe polyhydroxylated aliphatic hydrocarbon or the mixture thereof withthe chlorinating agent may be carried out in apparatus which is made ofor covered with materials that are resistant to chlorinating agents, asdescribed in the patent application entitled “Process for preparing achlorohydrin in corrosion-resistant apparatus”, filed in the name ofSOLVAY SA on the same day as the present application, and the content ofwhich is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinthat includes a step in which a polyhydroxylated aliphatic hydrocarbon,an ester of a polyhydroxylated aliphatic hydrocarbon or a mixturethereof is subjected to reaction with a chlorinating agent containinghydrogen chloride and to at least one other step carried out in anapparatus made of or covered with materials resistant to thechlorinating agent, under the conditions in which that step is realized.Mention is made more particularly of metallic materials such asenamelled steel, gold and tantalum and of non-metallic materials such ashigh-density polyethylene, polypropylene, poly(vinylidene fluoride),polytetrafluoroethylene, perfluoroalkoxyalkanes and poly(perfluoropropylvinyl ether), polysulphones and polysulphides, and unimpregnated andimpregnated graphite.

In the process for preparing a chlorohydrin according to the invention,the reaction of a polyhydroxylated aliphatic hydrocarbon, an ester ofpolyhydroxylated aliphatic hydrocarbon, an ester of polyhydroxylatedaliphatic hydrocarbon or a mixture thereof with the chlorinating agentmay be carried out in a reaction medium, as described in the applicationentitled “Continuous Process for Preparing Chlorohydrins”, filed in thename of SOLVAY SA on the same day as the present application, and thecontent of which is incorporated here by reference.

Particular mention is made of a continuous process for producingchlorohydrin in which a polyhydroxylated aliphatic hydrocarbon, an esterof a polyhydroxylated aliphatic hydrocarbon or a mixture thereof isreacted with a chlorinating agent and an organic acid in a liquidreaction medium whose steady-state composition comprisespolyhydroxylated aliphatic hydrocarbon and esters of polyhydroxylatedaliphatic hydrocarbon for which the sum of the amounts, expressed inmoles of polyhydroxylated aliphatic hydrocarbon, is greater than 1.1 mol% and less than or equal to 30 mol %, the percentage being based on theorganic part of the liquid reaction medium.

The organic part of the liquid reaction medium consists of all of theorganic compounds of the liquid reaction medium, in other words thecompounds whose molecule contains at least one carbon atom.

In the process for preparing a chlorohydrin according to the invention,the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon or the mixture thereof and thechlorinating agent may be carried out in the presence of a catalyst asdescribed in application WO 2005/054167 of SOLVAY SA from page 6 line 28to page 8 line 5.

Mention is made particularly of a catalyst based on a carboxylic acid oron a carboxylic acid derivative having an atmospheric boiling point ofgreater than or equal to 200° C., especially adipic acid and derivativesof adipic acid.

In the process for preparing a chlorohydrin according to the invention,the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon or the mixture thereof and thechlorinating agent may be carried out at a catalyst concentration,temperature and pressure and for residence times as described in theapplication WO 2005/054167 of SOLVAY SA from page 8 line 6 to page 10line 10.

Mention is made particularly of a temperature of at least 20° C. and notmore than 160° C., of a pressure of at least 0.3 bar and not more than100 bar and of a residence time of at least 1 h and not more than 50 h.

In the process for preparing a chlorohydrin according to the invention,the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon or the mixture thereof with thechlorinating agent may be carried out in the presence of a solvent asdescribed in application WO 2005/054167 of SOLVAY SA at page 11 lines 12to 36.

Mention is made particularly of organic solvents such as a chlorinatedorganic solvent, an alcohol, a ketone, an ester or an ether, anon-aqueous solvent which is miscible with the polyhydroxylatedaliphatic hydrocarbon, such as chloroethanol, chloropropanol,chloropropanediol, dichloropropanol, dioxane, phenol, cresol andmixtures of chloropropanediol and dichloropropanol, or heavy products ofthe reaction such as at least partially chlorinated and/or esterifiedoligomers of the polyhydroxylated aliphatic hydrocarbon.

In the process for preparing a chlorohydrin according to the invention,the reaction of the polyhydroxylated aliphatic hydrocarbon with thechlorinating agent may be carried out in the presence of a liquid phasecomprising heavy compounds other than the polyhydroxylated aliphatichydrocarbon, as described in the application entitled “Process forpreparing a chlorohydrin in a liquid phase”, filed in the name of SOLVAYSA on the same day as the present application, and the content of whichis incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinwherein a polyhydroxylated aliphatic hydrocarbon, an ester ofpolyhydroxylated aliphatic hydrocarbon or a mixture thereof is subjectedto reaction with a chlorinating agent in the presence of a liquid phasecomprising heavy compounds other than the polyhydroxylated aliphatichydrocarbon and having a boiling temperature under a pressure of 1 barabsolute of at least 15° C. more than the boiling temperature of thechlorohydrin under a pressure of 1 bar absolute.

In the process for preparing a chlorohydrin according to the inventionthe reaction of the polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon or the mixture thereof with thechlorinating agent is preferably carried out in a liquid reactionmedium. The liquid reaction medium may be a single-phase or multi-phasemedium.

The liquid reaction medium is composed of all of the dissolved ordispersed solid compounds, dissolved or dispersed liquid compounds anddissolved or dispersed gaseous compounds at the temperature of thereaction.

The reaction medium comprises the reactants, the catalyst, the solvent,the impurities present in the reactants, in the solvent and in thecatalyst, the reaction intermediates, the products and the by-productsof the reaction.

By reactants are meant the polyhydroxylated aliphatic hydrocarbon, theester of polyhydroxylated aliphatic hydrocarbon and the chlorinatingagent.

Among the impurities present in the polyhydroxylated aliphatichydrocarbon mention may be made of carboxylic acids, salts of carboxylicacids, esters of fatty acid with the polyhydroxylated aliphatichydrocarbon, esters of fatty acids with the alcohols used in thetransesterification, and inorganic salts such as alkali metal oralkaline earth metal sulphates and chlorides.

When the polyhydroxylated aliphatic hydrocarbon is glycerol, theimpurities in the glycerol that may be mentioned include carboxylicacids, salts of carboxylic acids, fatty acid esters such as mono-, di-and triglycerides, esters of fatty acids with the alcohols used in thetransesterification and inorganic salts such as alkali metal or alkalineearth metal sulphates and chlorides.

Among the reaction intermediates mention may be made ofmonochlorohydrins of the polyhydroxylated aliphatic hydrocarbon andtheir esters and/or polyesters, the esters and/or polyesters of thepolyhydroxylated aliphatic hydrocarbon and the esters ofpolychlorohydrins.

When the chlorohydrin is dichloropropanol, the reaction intermediatesthat may be mentioned include glycerol monochlorohydrin and its estersand/or polyesters, the esters and/or polyesters of glycerol and theesters of dichloropropanol.

The ester of polyhydroxylated aliphatic hydrocarbon may therefore be, ateach instance, a reactant, an impurity of the polyhydroxylated aliphatichydrocarbon or a reaction intermediate.

By products of the reaction are meant the chlorohydrin and water. Thewater may be the water formed in the chlorination reaction and/or waterintroduced into the process, for example via the polyhydroxylatedaliphatic hydrocarbon and/or the chlorinating agent, as described in theapplication WO 2005/054167 of SOLVAY SA at page 2 lines 22 to 28 to page3 lines 20 to 25, at page 5 lines 7 to 31 and at page 12 lines 14 to 19.

Among the by-products mention may be made for example of the partiallychlorinated and/or esterified oligomers of the polyhydroxylatedaliphatic hydrocarbon.

When the polyhydroxylated aliphatic hydrocarbon is glycerol, theby-products that may be mentioned include, for example, the partiallychlorinated and/or esterified oligomers of glycerol.

The reaction intermediates and the by-products may be formed in thedifferent steps of the process, such as, for example, during the step ofpreparing the chlorohydrin and during the steps of separating off thechlorohydrin.

The liquid reaction medium may therefore contain the polyhydroxylatedaliphatic hydrocarbon, the chlorinating agent in solution or dispersionin the form of bubbles, the catalyst, the solvent, the impuritiespresent in the reactants, in the solvent and in the catalyst, such asdissolved or solid salts, for example, the reaction intermediates, theproducts and the by-products of the reaction.

Steps (a), (b) and (c) of the process according to the invention may becarried out in batch mode or in continuous mode. It is preferred tocarry out all of the steps in continuous mode.

In the preparation process according to the invention, the organic acidmay be a product originating from the process for preparing thepolyhydroxylated aliphatic hydrocarbon, or a product not originatingfrom this process. In this latter case the product in question may be anorganic acid which is used in order to catalyse the reaction of thepolyhydroxylated aliphatic hydrocarbon with the chlorinating agent,and/or an acid generated in the process for preparing the chlorohydrin.Consideration is given, for example, to acids generated starting fromaldehydes present in the polyhydroxylated aliphatic hydrocarbon orformed during the preparation of the chlorohydrin. The organic acid mayalso be a mixture of an organic acid originating from the process forpreparing the polyhydroxylated aliphatic hydrocarbon, and an organicacid not originating from the process for preparing the polyhydroxylatedaliphatic hydrocarbon.

In the process according to the invention, the esters of thepolyhydroxylated aliphatic hydrocarbon may originate from the reactionbetween the polyhydroxylated aliphatic hydrocarbon and the organic acid,before, during or within the steps which follow the reaction with thechlorinating agent.

In the process according to the invention, the separation of thechlorohydrin and of the other compounds from the reaction mixture may becarried out in accordance with the methods as described in theapplication WO 2005/054167 of SOLVAY SA from page 12 line 1 to page 16line 35 and page 18 lines 6 to 13. These other compounds are thosementioned above and include unconsumed reactants, the impurities presentin the reactants, the catalyst, the solvent, the reaction intermediates,the water and the by-products of the reaction.

Particular mention is made of separation by azeotropic distillation of awater/chlorohydrin/chlorinating agent mixture under conditions whichminimize the losses of chlorinating agent, followed by isolation of thechlorohydrin by decantation.

In the process for preparing a chlorohydrin according to the invention,the isolation of the chlorohydrin and of the other compounds from thereaction mixture may be carried out in accordance with methods of thekind described in patent application EP 05104321.4, filed in the name ofSOLVAY SA on 20 May 2005 and the content of which is incorporated hereby reference. A separation method including at least one separatingoperation intended to remove the salt from the liquid phase isparticularly preferred.

Particular mention is made of a process for preparing a chlorohydrin byreacting a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof with achlorinating agent wherein the polyhydroxylated aliphatic hydrocarbon,an ester of the polyhydroxylated aliphatic hydrocarbon or a mixturethereof that is used comprises at least one solid or dissolved metalsalt, the process including a separation operation intended to removepart of the metal salt. Mention is made more particularly of a processfor preparing a chlorohydrin by reacting a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof with a chlorinating agent wherein the polyhydroxylatedaliphatic hydrocarbon, an ester of a polyhydroxylated aliphatichydrocarbon or a mixture thereof that is used comprises at least onechloride and/or a sodium and/or potassium sulphate and in which theseparating operation intended to remove part of the metal salt is afiltering operation. Particular mention is also made of a process forpreparing a chlorohydrin wherein (a) a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof is subjected to reaction with a chlorinating agent in areaction mixture, (b) continuously or periodically, a fraction of thereaction mixture containing at least water and the chlorohydrin isremoved, (c) at least a part of the fraction obtained in step (b) isintroduced into a distillation step and (d) the reflux ratio of thedistillation step is controlled by providing water to the saiddistillation step. Mention is made very particularly of a process forpreparing a chlorohydrin wherein (a) a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof is subjected to reaction with hydrogen chloride in areaction mixture, (b) continuously or periodically, a fraction of thereaction mixture containing at least water and chlorohydrin is removed,(c) at least part of the fraction obtained in step (b) is introducedinto a distillation step in which the ratio between the hydrogenchloride concentration and the water concentration in the fractionintroduced into the distillation step is smaller than the hydrogenchloride/water concentration ratio in the binary azeotropic hydrogenchloride/water composition at the distillation temperature and pressure.

In the process for preparing a chlorohydrin according to the invention,the separation of the chlorohydrin and of the other compounds from thereaction mixture from chlorination of the polyhydroxylated aliphatichydrocarbon may be carried out in accordance with methods as describedin the application entitled “Process for preparing a chlorohydrin”,filed in the name of SOLVAY SA on the same day as the presentapplication, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrinwhich comprises the following steps: (a) a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof is reacted with a chlorinating agent and an organic acidso as to give a mixture containing the chlorohydrin and esters of thechlorohydrin, (b) at least part of the mixture obtained in (a) issubjected to one or more treatments subsequent to step (a), and (c) thepolyhydroxylated aliphatic hydrocarbon is added to at least one of thesteps subsequent to step (a), in order to react at a temperature greaterthan or equal to 20° C. with the esters of the chlorohydrin, so as toform, at least partly, esters of the polyhydroxylated aliphatichydrocarbon. Mention is made more particularly of a process in which thepolyhydroxylated aliphatic hydrocarbon is glycerol and the chlorohydrinis dichloropropanol.

In the process for preparing a chlorohydrin according to the invention,the separation of the chlorohydrin and the other compounds from thereaction mixture from chlorination of the polyhydroxylated aliphatichydrocarbon may be carried out in accordance with methods as describedin the application entitled “Process for preparing a chlorohydrinstarting from a polyhydroxylated aliphatic hydrocarbon”, filed in thename of SOLVAY SA on the same day as the present application, and thecontent of which is incorporated here by reference.

Particular mention is made of a process for preparing chlorohydrin byreacting a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof with achlorinating agent in a reactor which is supplied with one or moreliquid streams containing less than 50% by weight of thepolyhydroxylated aliphatic hydrocarbon, of the ester of polyhydroxylatedaliphatic hydrocarbon or of the mixture thereof relative to the weightof the entirety of the liquid streams introduced into the reactor. Moreparticular mention is made of a process comprising the following steps:(a) a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof is reactedwith a chlorinating agent so as to give at least one mixture containingthe chlorohydrin, water and the chlorinating agent, (b) at least afraction of the mixture formed in step (a) is removed, and (c) thefraction removed in step (b) is subjected to an operation ofdistillation and/or stripping wherein the polyhydroxylated aliphatichydrocarbon is added in order to isolate, from the fraction removed instep (b), a mixture containing water and the chlorohydrin and exhibitinga reduced chlorinating agent content as compared with the fractionremoved in step (b).

In the process for preparing a chlorohydrin according to the invention,the separation of the chlorohydrin and of the other compounds from thereaction mixture from chlorination of the polyhydroxylated aliphatichydrocarbon may be carried out in accordance with methods as describedin the application entitled “Process for converting polyhydroxylatedaliphatic hydrocarbons into chlorohydrins”, filed in the name of SOLVAYSA on the same day as the present application, and the content of whichis incorporated here by reference. Particular mention is made of aprocess for preparing a chlorohydrin that comprises the following steps:(a) a polyhydroxylated aliphatic hydrocarbon, an ester of apolyhydroxylated aliphatic hydrocarbon or a mixture thereof is reactedwith a chlorinating agent so as to give a mixture containing thechlorohydrin, chlorohydrin esters and water, (b) at least a fraction ofthe mixture obtained in step (a) is subjected to a distillation and/orstripping treatment so as to give a portion concentrated in water, inchlorohydrin and in chlorohydrin esters, and (c) at least a fraction ofthe portion obtained in step (b) is subjected to a separating operationin the presence of at least one additive so as to obtain a moietyconcentrated in chlorohydrin and in chlorohydrin esters and containingless than 40% by weight of water.

The separating operation is more particularly a decantation.

In the process according to the invention, when the chlorohydrin ischloropropanol, it is generally employed in the form of a mixture ofcompounds comprising the isomers of 1-chloropropan-2-ol and2-chloropropan-1-ol. This mixture generally contains more than 1% byweight of the two isomers, preferably more than 5% by weight andparticularly more than 50%. The mixture commonly contains less than99.9% by weight of the two isomers, preferably less than 95% by weightand more particularly less than 90% by weight. The other constituents ofthe mixture may be compounds originating from the processes forpreparing the chloropropanol, such as residual reactants, reactionby-products, solvents and, in particular, water.

The mass ratio of the isomers, 1-chloropropan-2-ol and2-chloropropan-1-ol, is commonly greater than or equal to 0.01,preferably greater than or equal to 0.4. This ratio is commonly lessthan or equal to 99 and preferably less than or equal to 25.

In the process according to the invention, when the chlorohydrin ischloroethanol, it is generally employed in the form of a mixture ofcompounds comprising the 1-chloroethan-2-ol isomer. This mixturegenerally contains more than 1% by weight of the isomer, preferably morethan 5% by weight and particularly more than 50%. The mixture commonlycontains less than 99.9% by weight of the isomer, preferably less than95% by weight and more particularly less than 90% by weight. The otherconstituents of the mixture may be compounds originating from theprocesses for preparing the chloroethanol, such as residual reactants,reaction by-products, solvents and, in particular, water.

In the process according to the invention, when the chlorohydrin ischloropropanediol, it is generally employed in the form of a mixture ofcompounds comprising the isomers of 1-chloropropane-2,3-diol and2-chloropropane-1,3-diol. This mixture generally contains more than 1%by weight of the two isomers, preferably more than 5% by weight andparticularly more than 50%. The mixture commonly contains less than99.9% by weight of the two isomers, preferably less than 95% by weightand more particularly less than 90% by weight. The other constituents ofthe mixture may be compounds originating from the processes forpreparing the chloropropanediol, such as residual reactions, reactionby-products, solvents and, in particular, water.

The mass ratio between the 1-chloropropane-2,3-diol and2-chloropropane-1,3-diol isomers is commonly greater than or equal to0.01, preferably greater than or equal to 0.4. This ratio is commonlyless than or equal to 99 and preferably less than or equal to 25. In theprocess according to the invention, when the chlorohydrin isdichloropropanol, it is generally employed in the form of a mixture ofcompounds comprising the isomers of 1,3-dichloropropan-2-ol and2,3-dichloropropan-1-ol. This mixture generally contains more than 1% byweight of the two isomers, preferably more than 5% by weight and inparticular more than 50%. The mixture commonly contains less than 99.9%by weight of the two isomers, preferably less than 95% by weight andmore particularly less than 90% by weight. The other constituents of themixture may be compounds originating from the processes for preparingthe dichloropropanol, such as residual reactants, reaction by-products,solvents and, in particular, water.

The mass ratio between the 1,3-dichloropropan-2-ol and2,3-dichloropropan-1-ol isomers is commonly greater than or equal to0.01, often greater than or equal to 0.4, frequently greater than orequal to 1.5, preferably greater than or equal to 3.0, more preferablygreater than or equal to 7.0 and with very particular preference greaterthan or equal to 20.0. This ratio is commonly less than or equal to 99and preferably less than or equal to 25.

The chlorohydrin obtained in the process according to the invention mayinclude a heightened amount of halogenated ketones, in particular ofchloroacetone, as described in the patent application FR 05.05120 of 20May 2005, filed in the name of the applicant, and the content of whichis incorporated here by reference. The halogenated ketone content may bereduced by subjecting the chlorohydrin obtained in the process accordingto the invention to an azeotropic distillation in the presence of wateror by subjecting the chlorohydrin to a dehydrochlorination treatment asdescribed in this application from page 4 line 1 to page 6 line 35.

Particular mention is made of a process for preparing an epoxide whereinhalogenated ketones are formed as by-products and which comprises atleast one treatment of removal of at least a portion of the halogenatedketones formed. Mention is made more particularly of a process forpreparing an epoxide by dehydrochlorinating a chlorohydrin of which atleast one fraction is prepared by chlorinating a polyhydroxylatedaliphatic hydrocarbon, an ester of a polyhydroxylated aliphatichydrocarbon or a mixture thereof, a treatment of dehydrochlorination anda treatment by azeotropic distillation of a water/halogenated ketonemixture, which are intended to remove at least a portion of thehalogenated ketones formed, and a process for preparing epichlorohydrinwherein the halogenated ketone formed is chloroacetone.

The chlorohydrin obtained in the process according to the invention maybe subjected to a dehydrochlorination reaction in order to produce anepoxide, as described in the patent applications WO 2005/054167 and FR05.05120, both filed in the name of SOLVAY SA.

The term “epoxide” is used herein to describe a compound containing atleast one oxygen bridged on a carbon-carbon bond. Generally speaking,the carbon atoms of the carbon-carbon bond are adjacent and the compoundmay contain atoms other than carbon atoms and oxygen atoms, such ashydrogen atoms and halogens. The preferred epoxides are ethylene oxide,propylene oxide and epichlorohydrin.

The dehydrochlorination of the chlorohydrin may be carried out asdescribed in the application entitled “Process for preparing an epoxidestarting from a polyhydroxylated aliphatic hydrocarbon and achlorinating agent”, filed in the name of SOLVAY SA on the same day asthe present application, and the content of which is incorporated hereby reference.

Particular mention is made of a process for preparing an epoxide whereina reaction mixture resulting from the reaction between apolyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylatedaliphatic hydrocarbon or a mixture thereof with a chlorinating agent,the reaction mixture containing at least 10 g of chlorohydrin per kg ofreaction mixture, is subjected to a subsequent chemical reaction withoutintermediate treatment.

Mention is also made of the preparation of an epoxide that comprises thefollowing steps: (a) a polyhydroxylated aliphatic hydrocarbon, an esterof a polyhydroxylated aliphatic hydrocarbon or a mixture thereof isreacted with a chlorinating agent and an organic acid so as to form thechlorohydrin and chlorohydrin esters in a reaction mixture containingthe polyhydroxylated aliphatic hydrocarbon, the ester ofpolyhydroxylated aliphatic hydrocarbon, water, the chlorinating agentand the organic acid, the reaction mixture containing at least 10 g ofchlorohydrin per kg of reaction mixture, (b) at least a fraction of thereaction mixture obtained in step (a), this fraction having the samecomposition as the reaction mixture obtained in step (a), is subjectedto one or more treatments in steps subsequent to step (a), and (c) abasic compound is added to at least one of the steps subsequent to step(a) in order to react at least partly with the chlorohydrin, thechlorohydrin esters, the chlorinating agent and the organic acid so asto form the epoxide and salts.

The process for preparing the chlorohydrin according to the invention,may be integrated within an overall plan for preparation of an epoxide,as described in the application entitled “Process for preparing anepoxide starting from a chlorohydrin”, filed in the name of SOLVAY SA onthe same day as the present application, and the content of which isincorporated here by reference.

Particular mention is made of a process for preparing an epoxide thatcomprises at least one step of purification of the epoxide formed, theepoxide being at least partly prepared by a process ofdehydrochlorinating a chlorohydrin, the latter being at least partlyprepared by a process of chlorinating a polyhydroxylated aliphatichydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or amixture thereof.

In a first embodiment of the process according to the invention a partof the mixture obtained in step (a) is withdrawn and this part issubject to oxidation at a temperature greater than or equal to 800° C.during the withdrawal.

In a second embodiment of the process according to the invention a partof the mixture obtained in step (a) is withdrawn and at least part ofthe mixture obtained in step (a) is subjected to one or more treatmentsin steps subsequent to step (a) so as to give one or more treated parts,and at least one of the treated parts is subjected to oxidation at atemperature greater than or equal to 800° C.

The treatment of step (b) may be a separating operation, for example adecantation operation, or a filtration, centrifugation, extraction,washing, evaporation, stripping, distillation, adsorption or absorptionoperation or combinations of at least two thereof.

By oxidation is meant a reaction in the presence of at least oneoxidizing agent. The oxidizing agent may be selected from water, oxygen,oxides of chlorine, oxides of nitrogen, mixtures thereof with oneanother and their mixtures with nitrogen.

The oxidation temperature is greater than or equal to 800° C. and moreparticularly greater than or equal to 1000° C. This temperature isgenerally less than or equal to 10 000° C. and often less than or equalto 1500° C., frequently less than or equal to 1450° C. and moreparticularly less than or equal to 1400° C. High-temperature oxidationis generally carried out at a pressure which is generally greater thanor equal to 0.1 bar, often greater than or equal to 0.5 bar and moreparticularly greater than or equal to 0.8 bar. This pressure isgenerally less than or equal to 3 bar, preferably less than or equal to2.5 bar and frequently less than or equal to 1 bar. The duration of theoxidation reaction is generally greater than or equal to 1.0 s, oftengreater than or equal to 1.5 s and more particularly greater than orequal to 1 s. This duration is generally less than or equal to 20 s,frequently less than or equal to 15 s and in particular less than orequal to 10 s. An example of an oxidation process at a temperaturegreater than or equal to 800° C. is that in which organic chlorinecompounds and oxygen compounds in the form of carbon dioxide, hydrogenchloride and water are oxidized. Another example of an oxidation processat a temperature greater than or equal to 800° C. is that in whichorganic chlorine compounds and oxygen compounds are oxidized in a plasmaat a temperature which is generally greater than or equal to 3000° C.

In the process according to the invention the chlorinating agent,hydrogen chloride for example, generated in step (c) may be recycled tostep (a) after optional processing. This processing may consist forexample in an operation of absorption in an aqueous solution, followedby optional partial desorption of gaseous hydrogen chloride. Thisrecycling is particularly advantageous when the chlorinating agentcontains hydrogen chloride.

A description of high-temperature oxidation processes may be found inthe reference “Ullmann's Encyclopedia of Industrial Chemistry, Fifth,Completely Revised Edition, 1985, Volume A13, pages 292-293”.

In the process according to the invention, the polyhydroxylatedaliphatic hydrocarbon is preferably glycerol and the chlorohydrin ispreferably dichloropropanol.

When the chlorohydrin is dichloropropanol, the process according to theinvention may be followed by preparation of epichlorohydrin bydehydrochlorination of dichloropropanol, and the epichlorohydrin may beused in the production of epoxy resins.

FIG. 1 shows a particular scheme of plant which can be used forimplementing the separating process according to the invention.

A reactor (4) is supplied in continuous mode or in batch mode with apolyhydroxylated aliphatic hydrocarbon, an ester of polyhydroxylatedaliphatic hydrocarbon or a mixture thereof, via line (1), and withcatalyst via line (2); chlorinating agent is supplied in continuous modeor in batch mode via line (3); a distillation column (6) is supplied vialine (5) with vapours produced in reactor (4); a stream is taken offfrom column (6) via line (7) and is introduced into a condenser (8); thestream obtained from the condenser is introduced via line (9) into aphase separator (10), in which aqueous and organic phases are separated.A fraction of the separated aqueous phase is optionally recycled vialine (11) to the top of the column in order to maintain the reflux.Fresh water may be introduced into line (11) via line (12). Theproduction of chlorohydrin is distributed between the organic phasetaken off via line (14) and the aqueous phase taken off via line (13).The residue from column (6) may be recycled to reactor (4) via line(15). A fraction of the heavy products is taken off from reactor (4) viathe purge (16) and is introduced via line (17) into an evaporator (18),in which a partial operation of evaporation is conducted, for example,by heating or by gas scavenging with nitrogen or with water vapour; thegaseous phase containing the majority of the chlorinating agent fromstream (17) is recycled via line (19) to column (6) or via line (20) toreactor (4); a distillation or stripping column (22) is supplied withthe liquid phase coming from stripping apparatus (18) via line (21); andthe major part of the chlorohydrin is recovered at the top of column(22) via line (23).

The residue containing heavy compounds is recycled to reactor (4) vialine (31); a fraction of these heavy compounds is taken off and isintroduced into a pretreatment unit (34) via line (32); the heavycompounds which can be utilized in the process for chlorinating thepolyhydroxylated aliphatic hydrocarbon are recycled to reactor (4) vialine (35), and the non-utilizable heavy compounds are passed via line(36) into a high-temperature oxidizing unit (37) which is supplied withair via line (38), and from which a stream containing hydrogen chlorideis taken off via line (41). The oxidizing unit may be optionallysupplied with another stream of combustible substances (39) containing,optionally, chlorine compounds from other preparations, such as thesynthesis of chloroalkanes, the synthesis of tetrachloromethane andperchloroethylene by chlorinolysis, and the synthesis of1,2-dichloroethane. Provision of water or of an aqueous solution ofhydrogen chloride may be optionally carried out via line (40) in orderto reduce the chlorine content of the stream containing the hydrogenchloride produced. The hydrogen chloride obtained from thehigh-temperature oxidizing unit (37) is optionally recycled to thechlorinating agent supply of reactor (4) via line (42). The filteringcolumn (25) is in that case short-circuited.

Optionally the heavy compounds obtained from column (22) are passed vialine (24) to filtering unit (25), in which the liquid and solid phasesare separated; a fraction of the liquid phase is recycled via line (26)to reactor (4). The recycling of the heavy compounds to reactor (4) vialine (31) is in that case short-circuited. The solid may be taken offfrom filtering unit (25) via line (27) in the form of a solid or asolution. Solvents may be added to filtering unit (25) via lines (28)and (29) for washing and/or dissolving the solid, and may be taken offvia line (27). A fraction of the liquid phase recycled to reactor (4)via line (26) is taken off and passed to a pretreatment unit (34) vialine (33).

Optionally a stream is taken off from purge (16) and introduced via line(30) into filtering unit (25). Stripping apparatus (18) and distillationcolumn (22) are in that case short-circuited.

Optionally the stream taken off from purge (16) directly suppliespretreatment unit (34). The filtering column is in that caseshort-circuited.

Optionally the unit for pretreating heavy compounds (34) isshort-circuited.

1. Process for preparing a chlorohydrin, comprising: (a) reacting a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof whose alkali metal and/or alkaline earth metal content is greater than or equal to 0.1 μg/kg and less than or equal to 5 g/kg, a chlorinating agent and an organic acid so as to give a mixture containing at least chlorohydrin and other compounds, (b) subjecting at least part of the mixture obtained in step (a) to one or more treatments, said treatments comprising at least an oxidation at a temperature greater than or equal to 800° C. to produce HCl and optionally at least one separating operation selected from decantation, filtration, centrifugation, extraction, washing, evaporation, stripping, distillation and adsorption operations.
 2. Process according to claim 1, wherein the alkali metals and/or alkaline earth metals are present in the form of chlorides, sulphates or mixtures thereof.
 3. Process according to claim 2, wherein the polyhydroxylated aliphatic hydrocarbon, ester of a polyhydroxylated aliphatic hydrocarbon or mixture thereof contains sodium chloride.
 4. Process according to claim 2, wherein the polyhydroxylated aliphatic hydrocarbon, ester of a polyhydroxylated aliphatic hydrocarbon or mixture thereof contains potassium chloride.
 5. Process according to claim 1, wherein the alkali metal and/or alkaline earth metal content of the polyhydroxylated aliphatic hydrocarbon, of the ester of polyhydroxylated aliphatic hydrocarbon or of the mixture thereof is less than or equal to 1 g/kg.
 6. Process according to claim 1, wherein the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is obtained starting from renewable raw materials.
 7. Process according to claim 1, wherein the polyhydroxylated aliphatic hydrocarbon is reacted with said chlorinating agent and said organic acid and is selected from ethylene glycol, propylene glycol, chloropropanediol, glycerol and mixtures of at least two thereof.
 8. Process according to claim 1, wherein the chlorohydrin is selected from chloroethanol, chloropropanol, chloropropanediol, dichloropropanol and mixtures of at least two thereof.
 9. Process according to claim 1, wherein the polyhydroxylated aliphatic hydrocarbon is glycerol and the chlorohydrin is dichloropropanol.
 10. Process according to claim 1, wherein the chlorinating agent is gaseous hydrogen chloride.
 11. Process according to claim 1, wherein a part of the mixture obtained in step (a) is withdrawn and is subjected to oxidation at a temperature greater than or equal to 800° C. during the withdrawal.
 12. Process according to claim 1, wherein the oxidation is carried out at a temperature less than or equal to 1500° C., at a pressure greater than or equal to 0.1 and less than or equal to 2 bar and for a duration greater than or equal to 1.5 seconds and less than or equal to 20 seconds.
 13. Process according to claim 1, wherein the oxidation is carried out in the presence of at least one oxidizing agent selected from water, oxygen, oxides of chlorine, oxides of nitrogen, mixtures thereof with one another and their mixtures with nitrogen.
 14. Process according to claim 13, wherein a gas containing hydrogen chloride is generated during the oxidation.
 15. Process according to claim 14, wherein the hydrogen chloride generated is separated off and recycled to (a) after optional processing.
 16. Process according to claim 1, wherein (a) and (b) are conducted continuously.
 17. Process for preparing dichloropropanol, comprising: (a) reacting glycerol whose alkali metal and/or alkaline earth metal content is greater than or equal to 0.1 μg/kg and less than or equal to 5 g/kg, hydrogen chloride and an organic acid so as to give a mixture containing at least dichloropropanol and by-products, (b) at least a fraction of the mixture obtained in (a) is withdrawn and said fraction is subjected to oxidation at a temperature greater than or equal to 1000° C. to produce HCl.
 18. Process according to claim 9, further comprising preparation of epichlorohydrin by dehydrochlorination of the dichloropropanol.
 19. Process according to claim 18, further comprising the preparation of an epoxy resin with the epichlorohydrin.
 20. Process according to claim 1, wherein at least part of the mixture is subjected to said separating operation, and wherein said at least part of the mixture is subjected to said oxidation before being subjected to said separating operation.
 21. Process according to claim 1, wherein at least part of the mixture is subjected to said separating operation, and wherein said at least part of the mixture is subjected to said oxidation after being subjected to said separating operation.
 22. Process according to claim 1, wherein the alkali metal and/or alkaline earth metal content of the polyhydroxylated aliphatic hydrocarbon, of the ester of polyhydroxylated aliphatic hydrocarbon or of the mixture thereof is less than or equal to 0.5 g/kg.
 23. Process according to claim 5, wherein the polyhydroxylated aliphatic hydrocarbon is glycerol and the chlorohydrin is dichloropropanol.
 24. Process according to claim 10, wherein the HCl generated during oxidation is recycled to (a) after optional processing.
 25. Process according to claim 17, wherein the HCl generated during oxidation is recycled to (a) after optional processing. 